Rotary mowers are designed for a wide range of mowing applications. In some mowers, a swing hitch is used for offsetting the mower to one side of a towing vehicle in order for the mower to reach under trees and shrubs.
A known design for this type of machine is in the form of dual rotary blades rotating side by side within a housing. A pair of swing arms are mounted on the housing for connection to a three point hitch. The offset of the mower is controlled by a hydraulic cylinder mounted on the housing and connected to one of the swing arms. Power is delivered to the mower from a tractor power take off shaft connected to a primary gearbox. Secondary gearboxes receive torque from the primary gearbox and drive the respective mower blades.
There are some disadvantages to this design. The hydraulic cylinder for controlling the swing arms extends to one side of the swing arm, so that the arm is only able to swing in one direction. This limits the mower to an offset to one side only of the tractor. Limitations are imposed on the amount of offset to avoid exceeding the recommended offset angle of the drive shaft assembly.